.\" Copyright (c) 2010 Kai Wang
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.\" $Id$
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.Dd April 17, 2010
.Os
.Dt DWARF_DIEOFFSET 3
.Sh NAME
.Nm dwarf_die_CU_offset ,
.Nm dwarf_die_CU_offset_range ,
.Nm dwarf_dieoffset ,
.Nm dwarf_get_cu_die_offset_given_cu_header_offset
.Nd return offsets of DWARF debugging information entries
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_die_CU_offset
.Fa "Dwarf_Die die"
.Fa "Dwarf_Off *ret_offset"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_die_CU_offset_range
.Fa "Dwarf_Die die"
.Fa "Dwarf_Off *cu_offset"
.Fa "Dwarf_Off *cu_length"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_dieoffset
.Fa "Dwarf_Die die"
.Fa "Dwarf_Off *ret_offset"
.Fa "Dwarf_Error *err"
.Fc
.Ft int
.Fo dwarf_get_cu_die_offset_given_cu_header_offset
.Fa "Dwarf_Debug dbg"
.Fa "Dwarf_Off in_cu_header_offset"
.Fa "Dwarf_Off *out_cu_die_offset"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
These functions are used to retrieve offsets for DWARF debugging
information entries.
.Pp
Function
.Fn dwarf_die_CU_offset
returns the offset of the debugging information entry referenced by
argument
.Ar die
relative to the start of its containing compilation unit.
Argument
.Ar ret_offset
should point to the location that is to hold the returned offset.
If argument
.Ar err
is non-NULL, it will be used to return an error descriptor in case of
an error.
.Pp
Function
.Fn dwarf_die_CU_offset_range
returns the section-relative offset and length of the compilation unit
containing the debugging information entry referenced by argument
.Ar die .
Argument
.Ar cu_offset
should point to a location that will hold the returned offset.
Argument
.Ar cu_length
should point to a location that will hold the returned length of the
compilation unit.
If argument
.Ar err
is non-NULL, it will be used to return an error descriptor in case of
an error.
.Pp
Function
.Fn dwarf_dieoffset
retrieves the section-relative offset of the debugging information
entry referenced by argument
.Ar die .
Argument
.Ar ret_offset
should point to a location that is to hold the returned
section-relative offset.
If argument
.Ar err
is non-NULL, it will be used to return an error descriptor in case of
an error.
.Pp
Function
.Fn dwarf_get_cu_die_offset_given_cu_header_offset
returns the offset for the debugging information entry for a
compilation unit, given an offset to the header of the compilation
unit.
Argument
.Ar dbg
should reference a valid debugging context allocated using
.Xr dwarf_init 3 .
Argument
.Ar in_cu_header_offset
contains the offset to the start of a compilation unit.
Argument
.Ar out_cu_die_offset
points to a location that will hold the returned offset.
If argument
.Ar err
is non-NULL, it will be used to return an error descriptor in case of
an error.
.Sh RETURN VALUES
On success, these functions returns
.Dv DW_DLV_OK .
In case of an error, these functions return
.Dv DW_DLV_ERROR
and set argument
.Ar err .
.Pp
Function
.Fn dwarf_get_cu_die_offset_given_cu_header_offset
returns
.Dv DW_DLV_NO_ENTRY
and sets argument
.Ar err
if there is no compilation unit located at the
offset specified in argument
.Ar in_cu_header_offset .
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Va cu_length ,
.Va cu_offset ,
.Va dbg ,
.Va die ,
.Va out_cu_die_offset
or
.Va ret_offset
was NULL.
.It Bq Er DW_DLE_NO_ENTRY
Argument
.Ar in_cu_header_offset
specified an unknown offset.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_next_cu_header 3 ,
.Xr dwarf_offdie 3
